1. Field of the Invention
The present invention relates to an electronic image pickup apparatus in which a zoom lens system having a reflective surface in an optical path is used.
2. Description of the Related Art
In recent years, instead of a silver halide film camera, a digital camera has been a mainstream which photographs an object by use of an electronic image pickup device such as a CCD image sensor or a CMOS type image sensor. Furthermore, the camera has a large number of categories in a broad range from a highly functional type for business to a compact popular type. In the present invention, the category of the compact popular type is especially noted.
A user of such a popular type of digital camera has a desire to enjoy photographing a broad range of scenes readily anytime and anywhere. Therefore, the user would like a digital camera which is conveniently carried with a good storage property in a clothing or bag pocket or the like and which has a small size in a thickness direction.
With regard to the size of the camera in the thickness direction, much weight is laid on a size of a lens barrel. Therefore, it is important to design a zoom lens system in consideration of thinning of the lens barrel.
There are several means for thinning the lens barrel, and one of the means is a zoom lens system in which an optical path is reflected by a reflective member such as a mirror or a prism disposed on the optical path to achieve the thinning.
This zoom lens system has a characteristic that a shape of the camera hardly changes during the photographing and during the carrying. The system also has various merits including design, robustness, applications of dust-proof construction or drip-proof construction, but to achieve the thinning is the largest merit. To further improve this merit, a measure of cutting a part of a lens in the thickness direction of the camera is employed. In Japanese Patent Application Laid-Open No. 2005-121,799, an example in which a part of the lens is cut in the thickness direction of the camera is disclosed.
However, in a case where such cutting of the lens is performed, a room between a ray (an effective ray) which reaches an effective region of an image pickup surface and an outer diameter of the lens is much reduced. Therefore, stray light strikes on a cut portion of the lens, is reflected or irregularly reflected, and easily reaches the effective region of the image pickup surface. So-called ghost or flare is generated.
When intensity of the ghost or flare is low as compared with brightness of an object image, the ghost or flare does not raise any problem in many cases. However, in another case, the user rarely accepts the ghost or flare favorably.